In general, at least one printed circuit board is equipped in an electronic device and elements with various shapes are mounted on these printed circuit boards. And 3-dimensional shape measurement apparatus is used to inspect defect of such elements.
Conventional 3-dimensional shape measurement apparatus uses a camera to capture a reflection image of a grid pattern light which is emitted from the lighting device, and is measures 3-dimensional shape of the target object such as printed circuit board by using the captured reflection image.
In such 3-dimensional shape measurement apparatus described above, an equivalent wavelength corresponding to a pitch interval of a grid pattern light emitted from the lighting device is proportional to an available height of measurement of a target object, therefore, it is not possible to unlimitedly increase the equivalent wavelength but increase within a predetermined range.
Therefore, it is impossible to measure a 3-dimensional shape of a target object when a height of a target object exceeds an available height which can be measured by a grid pattern light emitted from a lighting device.